vttablet mysql conn improvements#3933
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demmer merged 4 commits intovitessio:masterfrom May 17, 2018
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In order to better monitor how many times the tablet creates a new mysql connection and how long these attempts take, add another call to measure the timings of each Connect operation in the dbconn wrapper. Additionally record the timings and associated counts for any times when the connection to mysql fails to execute the handshake. Signed-off-by: Michael Demmer <mdemmer@slack-corp.com>
If the context deadline expires before the query has a chance to execute, the query killer will terminate the connection immediately after sending the query to mysql. Instead, add a check at the start of dbConn.execOnce and fail the query immediately if the context is already past the deadline. Signed-off-by: Michael Demmer <mdemmer@slack-corp.com>
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NB: I added simple unit tests but haven't yet tested this in a real environment. Will do that tomorrow. |
sougou
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May 16, 2018
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Change is good. One minor comment.
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| // Check if the context is already past its deadline before | ||
| // trying to execute the query. | ||
| if ctx.Done() != nil { |
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This check is not needed. If the channel is nil, it won't fire.
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Thanks -- removed (and verified it still works)
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Oh. I copied that from other parts of the code.
…-m
On May 15, 2018, at 5:36 PM, Sugu Sougoumarane ***@***.***> wrote:
@sougou commented on this pull request.
Change is good. One minor comment.
In go/vt/vttablet/tabletserver/connpool/dbconn.go:
> @@ -132,6 +132,16 @@ func (dbc *DBConn) execOnce(ctx context.Context, query string, maxrows int, want
dbc.current.Set(query)
defer dbc.current.Set("")
+ // Check if the context is already past its deadline before
+ // trying to execute the query.
+ if ctx.Done() != nil {
This check is not needed. If the channel is nil, it won't fire.
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As suggested in PR review there's no need for the extra check that ctx.Done() is none nil before selecting from it. Signed-off-by: Michael Demmer <mdemmer@slack-corp.com>
Previously it included all counts in the MySQLStats which now also tracks connections. Signed-off-by: Michael Demmer <mdemmer@slack-corp.com>
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May 16, 2018
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Add a couple of changes to improve visibility and robustness on the vttablet => mysql connection handling.
In order to better monitor how many times the tablet creates a new mysql connection and how long these attempts take, add another call to measure the timings of each Connect operation in the dbconn wrapper.
Additionally record the timings and associated counts for any times
when the connection to mysql fails to execute the handshake.
If the context deadline expires before the query has a chance to execute, the query killer will terminate the connection immediately after sending the query to mysql.
Instead, add a check at the start of dbConn.execOnce and fail the query immediately if the context is already past the deadline.